Method and apparatus for producing sheet glass



J. L. DRAKE March 8, 1932.

METHOD AND APPARATUS FOR PRODUCING SHEET GLASS Filed Sept. 18

glwue'ntoz' John L. DraKe dttomwg/ Patented Mar. 8, 1932 V a UN STATES P'ArtENr FFI C*E ,i

JOHNL. nnnxnor TOLEDO, oni inss enon TO nrnnnv ownns ronn GLASS COMPANY}. 4 or TOLEDO, OHIO, aconronerron OF- OHIO METHOD AND APPAnATUs Fee rnonnome' snnn'r GLASS Application filed Se temberis 192a Serial No. 393,458;

i This invention relates broadly to themanufacture of sheet glass and more particularly to a method of and apparatus for'forming sheet glass by an intermittent rolling Operaexceedingly long. For example, if the glass from where it is moved to and passed between a pair of forming rolls which function to reduce the glass to a sheet of substantially pre determined and uniform thickness. In the method. ust described, it is desirable tha-tthe molten glass passing to theforming rolls be rapidly reduced thereby to sheet form so as not to adversely affect the quality ofthe glass and also in order to speed up production,

VVhile it is expedient to'reduce the molten glass rapidly to'sheet form, it is not necessary this same high rate of speed and infact, such is undesirable for the reason that in this event, the annealing leer necessary would have'to be wererolled to sheet form at the rate'of sixty feet per minute and it required sixty minutes to anneal theglass, itwill be seen thatthe length of leer necessary wouldibe 3600 feet. The disadvantages incident to the construction, operation and maintenance of a leer of r this length'are' believed to be obvious;

In'its broad aspect, the present invention contemplates the provision of ainethod and apparatus whereby a massof molten glass may be'reduced to sheet form at a relatively high rate of s eed by an intermittentrolling operation anc the sheet subsequently, an-

nealed while traveling at a relatively slower speed. Thus, the invention aims to'providc such a method and apparatus which will cmv towards breakage of said sheet'due tOunbody those advantages incident to the rapid reduction of the molten glass to sheet form and. likewise those advantages which result from slower annealing ofthe glass.

- ,Another objectof the invent on is theiprovision-of such amethod andapp aratus wherethat the glass be annealed while traveling at.

in aplhrality of successive sheetsof glass are adapted to be formed at predetermined intervals and at. a relatively high. rate of it is formed into-and through the annealing leer, the speed of travel of the sheet through the leer being materiallyreduced duringthat' interim betweenthe formation of successive.

speed, each sheet being carried forwardly as this manner, the speed at which 'thesheet'is .7

caused'to pass through the leer will belpe riodically varied and during the greater por tion. of the time required for annealing, the sheet will travel through theleer at arelatively slow speed,

j Another 0b ect ofthe inventioniis vision of such a method and-apparatus of the above character whereinamore uniform cooling and annealing of the. glass sheet'may be had as the said sheet tr'avelsthrough the annealing leerftothe end that the sheet will be cooled simultaneously the same amount throughout its entire area and the gradual 7 reduction of the temperatureof the sheetwill be uniformly maintained so thattheentire sheet-will always be at fs'ubstaiitially the same temperature. i 1 Y i j Q A further objectof theinventionis the provision of an annealing leer of improved construction, divided or separated into a W plurality of individual chambers each being maintained at a constant temperature and the she'et being caused to travel throughfeach chamber at arela'tively slow speed and transferred from' one chamber to the adjacent chamber at a relatively higher speed, with the result that the sheet will be cooledand annealed uniformly and the forwarde'nd of the sheet willnot be caused to cool in" ad Vance of the rear end. Such cooling andIa-n healing of' the, sheet will reduce the forma tion of strains, in the sheet and thetendenc'y uniformcooling-and annealing to aminimum. I

7 Other objectsand advantages ofthe -inventaken in connection with the accompanying drawings. 7

In the drawings forming a part of this application and wherein like numerals are employed to designate like parts throughout the same,

Fig. 1 is a vertical longitudinal section through apparatus constructed in accordance with the present invention, showingthe forward end portion of the annealing leer,

Fig. 2 is a similar View showing the rear or outlet end portion of the annealing leer,

and

Fig. 3 is a plan view of theapparatus.

Referring to the drawings, 6 designates a receiver or support adapted to receive thereupon a mass or charge of molten glass which is to be reduced to sheet form. This mass of molten glass is preferably deposited upon the receiver when the same is in a substantially horizontal position as indicated by the broken lines in Fig. 1 from a pot or receptacle (not shown) within which the glass is preferably completely'melted and refined. Associated with one end of the receiver 6 are the sheet forming rolls 7 and 8 arranged relative to one another to create a sheet forming pass therebetween through which the molten glass is moved and reduced to a sheet 9 of substantially predetermined and uniform thickness. The receiver 6 and upper forming roll 7 are preferably mounted so that they are movable as a-unit about the axis of rotation of the lower forming roll 8. Thus, after the molten glass has been deposited upon the receiver 6 while in a horizontal position, the said receiver may be tilted to the position indicated bythe full lines to advance the glass downwardly between the forming rolls.

As pointed out above, it is desirable that the sheet of glass 9 be formed at a relatively high rate of speed and the rolls 7 and 8 are consequently rotated in a manner that their peripheral speed will be such that they will function to rapidly reduce the mass of molten glass to sheet form. One of the forming rolls 7 or 8 may be positively driven such as through suitable drive means 10 and the other forming roll driven from the positively driven roll through intermeshing gears 11 which are keyed to the shafts carrying the rolls.

A plurality of rolls 12 may be positioned as indicated to receive the glass sheet 9 issuing from between the forming rolls and to guide the same downwardly and into the horizontal plane.

The numeral 13 designates an annealing leer containing a large number of horizontally aligned rolls 14 which are positioned to receive the glass sheet thereupon as it leaves the rolls 12. The annealing leer 13 is divided or separated into a plurality of individual compartments or chambers, the first two chambers at the entrance end of the leer adjacent the forming means being designated 15 and 16 and the two end chambers adjacent the exit end of said leer 17 and 18. While only four chambers have been shown, it is to be understood that any desired number of chambers may be interposed between the chambers '16 and 17 dependent upon the length of leer preferred. The adjacent chambersor compartments are separated from one another by a vertical partition wall 19 having a slot therein through which the sheet may pass from one compartment into the next compartment.

All of the leer rolls 14 and likewise the rolls 12 are adapted'to be driven in unison at the same speedrand to accomplish this, each of saidrolls may have associated therewith a sprocket (not shown) about which is trained a sprocket chain 21 driven from a motor or other source of power. The forming rolls 7 and 8 may also be driven in unison with the rolls 12 and 14 from the same drive or they may be driven independently of said rolls by a separate driving means as herein disclosed.

The various leer chambers are adapted to be of gradually decreasing temperatures from the intake end of the leer to the outlet or exit end thereof and the temperature in each chamber may be controlled in any suitable manner such as by the use ofburners or the like 20. By way of example only, the temperature of the first chamber 15 adjacent the forming mechanism may be maintained at 1050 degrees Fahr., the next chamber 13 at 1000 degrees F ahr. and so on, with the last chamber 18 at the outlet end being 160 degrees Fahn, and the adjacent chamber 175 degrees F ahr. Thus, a suflicient number of chambers are adapted to be provided in order that the temperature in the succeeding chambers can be gradually decreased the desired number ofdegrees from the maximum temperature in chamber 15 to the minimum temperature in chamber 18. The temperature in any one chamber is adapted to be maintained separate and independently of the temperature in the remaining chambers and is also adapted to be held constant throughout the entire length thereof. 7

In the operation of the apparatus above described, the conveying rolls 12 and leer rolls 14 are adapted to be driven in unison intermittently at different but corresponding speeds. That is, during the reduction of the mass of molten glass to sheet form, the forming rolls 7 and 8 are adapted to be driven at a relatively high rate of speed to rapidly re duce the molten glass to sheet form and the conveying rolls 12 and leer rolls 14 are likewise driven at the same speed so that as the sheet is formed and deposited upon the latter rolls, it will be carried forwardly at a speed equal to the speed of formation thereof. After the entire sheet has been deposited upon the rolls 14 Within the first leer chamber 15,

- howeventhespeed of therolls 12 and 1 4 is materially reduced so that the sheetwill'be the drive for the forming rolls is coupled up withthe drive for rolls 12 and 14, the forms glass is rolled feet per minute.

carried forwardly at a relatively slower speed. This reduced speed is continued during the interim which elapses between the completion of one sheet and the rolling of the next succeeding sheet. I-lowever, upon the formation of a second sheet, the speedof' the rolls 12 and 14 is again increased or speeded up to receive the sheet; In this manner,

the speed of the conveying rolls and leer rolls is relatively high. during the formation of each sheet and relatively slower during the interim between the formation of successive sheets. The sheets are therefore caused to travel through the leer intermittently first at a relatively high rate of speed and then at a relatively slower rate of speed. In the event their surfaceswill move at the rate of sixty.

feet per 1ninute..;After. the entire sheet is supported upon the leer rolls 14 in chamber 15, the speed of the conveying and leer rolls is simultaneously reduced to say two feet per minute and the sheet carried forwardly through the leer at this reduced speed until it is desired to'form another sheet; 1 During the formation of the second sheet, however,

the speed of theconveying and leer rolls is.

again increased to sixty feet per minute so 1 that the already formedsheet will'be carried through the leer at. the rate of sixty'feet per minute so long as the second sheet isbeing formed or, in other words, for oneiminute Afterthe second sheet 1s completed andreceived within the leer, the speedof travel of the sheets beingcarried forwardly isagain reduced until it is desired to form a third sheet whereupon the above cycle of operations is repeated. Thus, the sheetis formed at, a

relatively high rate of speed and subsequent ly annealed while traveling first at a relative- 1y slowrspeed and then at arelatively high speed, It will be apparent, thatf-in'the event the sheet was formed at the rate of. sixty feet per minute andit toolr sixty; minutes to anneal the glass and the sheet was passed through the leer ata speed equal to the speed of formation thereof, the length of the leer necessary WOlllClhitVGflIfbB 3600-feet. According to'the present invention, however, the

length of leer necessary toproperlyanneal the. glass may be materially; reducedand broughtto-within a more practical and de- 'sirablelength; For. instance, let ius'gassume leer.

that with the. apparatus disclosed, one sheet of'glas's is adaptedto-berrolled or formed every seven minutes. The sheet is formedat the. rate of sixty. feet per minute and during 1 this minute the forming rolls 7 and 8,: conv'eying and leer3rolls12 andll4wrespectively together with any sheets which maybe sup ported upon the latter, will be travelingat this high rate of speed. Aslsoon as'the sheet is' received within the leer, however, such speed is reduced to two feet per-minuteand this speed of two feet per minute is maintained for the.fnext.succeeding six minutes. The sheet will therefore travel seventy-two feet in seven minutes. with an average speed of ten feetper minute-through the annealing quired to anneal the glassand the glass travels. through the .leer at an average speed of ten feet per minute,-theleerwould-be approximately 600 feet long, ,which'is not an impractical or undesirable length. In this jmanner, the sheet is .keptconstantly in motion at all times tolprevent sagging thereof and a continuous annealing operation ishad. While,

afterthe sheet-is formed and passed into the leer, it is at intervals caused to travel at a speedequal to the speed of formatiomyet the sheet is annealed while traveling at-an average speed much slower than the speed of formation thereof so that it may be accurately statedthat the sheet is" formed at'arelativelyhigh speed and subsequently annealed while travelingat a relatively slower speed.

,In tunnel leers of the general character herein disclosed, there is usually provided a single continuous throughout the length of the leer, .said-cham Therefore, if sixty 1 minutes be re-' chamber -extending her having agradually decreasing temperature from the intake end to the outlet end thereof; As a consequence,with leers of this j type, the forward end of the glass sheetpassing therethrough will be cooled in. advance of. therear end thereof. This is an undesirable jcondition and causes the setting up of strains inthe glass with resulting breakage.

Y As described hereinabove, the l'eer' 13 of the present invention is; divided transversely into a plurality of individual chambers, each being maintained ataconstant uniform temperature and the temperature in each succeeding chamber being relatively less than the temperature in the preceding chamber. The individual leer chambers are each adapted to be of such a length that'during one complete sheet forming cycle which, as above noted, is seven minutes, the sheetwill pass entirely through any one chambentobring the head or forward end of the. sheet closely adjacent the partition wall 19 separating that chamber from the nextsucceeding chamber. -More specifically,if aglass sheet sixty feet inf ilength is-rolled every seven minutes and lb takes one minuteto roll the sheet at the high rate .ofspeed and sixminutes in which the sheet is traveling at the relatively slower annealing speed, it will be seen that the sheet will travel at the rate of 72 feet in the seven minutes, so that each chamber should be 72 feet in length.

In carrying the invention into practice, the glass sheet will be reduced to sheet form within one minute and will pass into the first leer chamber 1 5 at this speed. As soon as the sheet is entirely received within the chamber, the speed of said sheet is materially reduced and the sheet caused to travel forwardly at the rate of approximately two feet per minute for the next six minutes which will bring the forward end of the sheet closely adjacent the partition 19 separating chamber 15 from chamber 16. A second sheet is then formed and during the formation of the second sheet, the leer rolls 14 are speed'ed up to the speed of sheet formation whereupon the first sheet within chamber 15 will be quickly transferredtherefrom into chamber 16. As soon as the second sheet is received within chamber 15, the speed of the leer rolls is reduced so that the first sheet will move slowly through chamber 16 while the second sheet moves slowly through chamber 15. During the formation of each succeeding sheet, the leer rolls are temporarily speeded up to quickly transfer the sheets passing through the annealing leer from one chamber to the next chamber, and during that interim between the format on of each succeeding sheet, the glass sheets within the leer will pass through their respective chambers at a relatively slow speed. In this manner, each sheet will be uniformly cooledthrough out its entire area as it passes through the successive leer chambers, and shoe the sheet is quickly transferred from one chamber to another, there will be little or no danger of the forward end of the sheet cooling in advance of the rear end. Therefore, the process herein PlOVlClGClWlll not only permit the rapid formation of the sheet and the subsequent slower annealing thereof, but will further facilitate and improve the annealing of the sheet in such a manner as to reduce the formation of strains in the glass and consequent breakage thereof.

It is to be understood that the form of the invention herewith shown and described is to be taken as the preferred embodiment of the same, and that various changes in the shape, size and arrangement of parts may be resorted to without departing from the spirit ofthe invention or the scope of the subjoined claims.

I claim:

1. The method of producing sheet glass, which consists in forming the sheet at a relatively predetermined speed, carrying the sheet forwardly as it is formed at a speed substantially equal to the speed of formation thereof, annealing the sheet, intermittently decreasing and then increasing the speed of travel. of thesheet-at predetermined intervals during the annealing thereof, and in maintaining a constant, uniform temperature around the sheet during the time it is traveling at its slow speed. a

2. The method of producing sheetglass, which consists in forming the sheet at a relatively predetermined speed, carrying the sheet forwardly as it is formed at a speed substantially equal to the speed offormation thereof, annealing the sheet, intermittently decreasing and then increasing the speed of travel of the sheet at predetermined intervals during the annealing thereof, and in carrying thesheet during the slow period of its travel through an annealing zone having a constant uniform temperature throughout.

3. The method of producing sheet glass, which consists in forming the sheet at a relatively predetermin d speed, carrying the sheet forwardly as it is formed at a speed substantially equal to the speed of formation thereof, annealing the sheet, intermittently decreasing and then increasing the speed of travel of the sheet at predetermined intervals during the annealing thereof, in passing the sheet progressively through a plurality of annealing zones, and in maintaining a constant uniform temperature in each zone with the temperature ineach succeeding zone being less than that of the preceding zone.

4. The method of producing sheet glass, which consists in forming the sheet at a relatively predetermined speed, carrying the sheet forwardly as it is formed at a speed substantially equal to the speed of formation thereof, annealing the sheet, intermittently decreasing and then increasing the speed of travel of the sheet at predetermined intervals during the annealing thereof, and in passing the sheet through a plurality of annealing zones, the sheet traveling through the zones at a relatively slow speed and being transferred from one zone to another zone at a relatively faster speed.

5. The method of producing sheet glass, which consists in forming the sheet at a relatively predetermined speed, carrying the sheet forwardlyas it-is formed at a speed substantially equal to the speed of formation thereof, annealing the sheet by passing it through a plurality of annealing zones, in maintaining the travel of the sheet through each zone at a relatively slow speed, and in speeding up the movement of the sheet during its transfer from one zone into the next zone. 7

6. The' method of producing sheet glass, which consists in forming a plurality of successive sheets of glass at predetermined intervals and at a relatively high rate of speed, passing each sheet as'it is formed into and through 'a series of annealing chambers, reducing the speed of travel of the sheet during that-interval between the formation of successive sheets to pass said sheet slowly through the-annealing chambers, and theni'ncreasing the speed of travel of the sheet dur-*' ing the formation of each succeeding sheet to quickly transfer the sheet from one cham: her into the next chamber. 1 i

7. The method of producing sheet glass,

which consists in forming a plurality of successive sheets of glass at predetermined intervals and at a relatively high rate of speed, j passing each sheet as it is formed into and through a series of annealing chambers, re-

ducing the'speed of travel of the sheet during that interval between the formation of successive sheets to pass said sheet slowly through the annealing chambers, and. in

maintainingeach chamber at a constant uniform temperature throughout with the succeeding chambers gradually decreasing .in' 7 temperature. p

8. In 'glass apparatus, sheet forming means, an annealing leer, means for dividing the leer transversely into a'plurality of'ina dividual chambers, means. for maintaining each chamber'at a substantially constant uniform temperature throughout with the suc- 'ceeding chambers gradually decreasing in temperature, means for receiving the sheet from the forming means and conveyingv it successively through said chambers, and means e for driving said conveying means alternately at difiere'nt'spee'ds so as to carry the sheet through each chamber at a relatively slow speed and to transfer the'she'et iromone' o i chamber at arelativechamber into the next 1y high speed.

Signed at Toledo, in the countyof Lucas i: and State of Ohio, this lthday of September, 1929. v

JOHN L. DRAKE. 

